温度、光照对秋葵褐腐病病原菌菌丝生长、孢子萌发的影响及其田间药剂防治效果评价

Effects of Temperature and Light on Mycelian Growth and Spore Germination of Okra Brown Rot Pathogen and Evaluation of Fungicides Control Effect in Field

了解病原菌在不同环境下生活的状态,是控制病害流行的基础。为了解褐腐病菌在黑龙江地区的发生条件,并找到有效的防治药剂,采用室内试验对影响菌丝和孢子萌发的温度、光照条件进行研究,并对6种药剂防治秋葵褐腐病的田间防治效果进行评价。室内试验结果表明:秋葵褐腐病病原菌菌丝在15~40 ℃条件下均可生长,而产孢温度为20~30 ℃;30 ℃条件下菌丝生长速度最快,产孢量最高,均分别显著高于其他条件下的菌落直径和产孢量。光照不利于菌丝生长,但有利于产孢;在0 h光照下菌丝生长最快,菌落直径最长,第3天达7.85 cm,但产孢量最低,为1.04×10^(7)个/mL,均分别与其他处理有显著性差异;24 h光照处理第3天菌落直径(7.15 cm)显著小于其他2个处理,而病原菌产孢量最大(4.64×10^(7)个/mL),显著高于其他2个处理。孢子萌发的最适温度是30 ℃,在此温度下2 h就可以完成孢子萌发,在25 ℃条件下5 h时孢子才开始萌发,在20 ℃条件下24 h后孢子仍无萌发迹象。通过田间试验,筛选出50%烯酰吗啉水分散粒剂、20%腐霉利悬浮剂和72%霜脲·锰锌可湿性粉剂这3种药剂对秋葵褐腐病的防治效果较好,其中,50%烯酰吗啉水分散粒剂600倍液、1 200倍液分别较对照药剂10%多抗霉素可湿性粉剂600倍液显著提高15.2百分点、14.2百分点,分别较对照药剂1 200倍液显著提高13.8百分点、12.8百分点;20%腐霉利悬浮剂600倍液、1 200倍液防治效果分别较对照药剂600倍液显著提高9.3百分点、11.8百分点,分别较对照药剂1 200倍液显著提高8.3百分点、10.8百分点;72%霜脲·锰锌可湿性粉剂防治效果也显著高于对照药剂。综上,秋葵褐腐病发生的适宜温度为25~30 ℃,黑龙江地区主要发病时期在6月末—7月初,生产中可选用50%烯酰吗啉水分散粒剂、20%腐霉利悬浮剂、72%霜脲·锰锌可湿性粉剂在病害发生初期交替进行防治,每7 d喷雾1次,连续施药3次,可有效控制病害的发生。

Understanding the living conditions of pathogenic bacteria in different environments is the foundation for controlling disease outbreaks.In order to understand the occurrence conditions of brown rot pathogen in Heilongjiang area and find effective control fungicides,laboratory experiments were conducted to study the temperature and light conditions affecting the germination of mycelium and spores,and the field control effects of six fungicides on okra brown rot were evaluated.The results of laboratory experiment showed that the pathogenic mycelium of the okra brown rot could grow under conditions of 15-40 ℃,while the sporulation temperature was between 20-30 ℃.Under the condition of 30 ℃,the mycelian growth rate was the fastest and the spore-output was the highest,which were both significantly higher than the colony diameter and spore-output under other conditions.Light was not conducive to mycelian growth,but was conducive to sporulation.Under 0 hour of light treatment,the mycelium grew most quickly and the colony diameter was the largest,reaching 7.85 cm on the 3rd day,while the spore-output was the lowest of 1.04×10^(7) cells/mL,which showed significant differences compared to other treatments.The mycelian growth rate was slowest under the 24 hours light treatment,with a colony diameter of 7.15 cm on the 3rd day,significantly smaller than the other two treatments,while pathogenic spore-output was the highest (4.64×10^(7) cells/mL),significantly higher than the other two treatments.The optimal temperature for spore germination was 30 ℃,and it could be completed within 2 hours at this temperature.Spores only begin to germinate after 5 hours at 25 ℃,and there was still no sign of germination after 24 hours at 20 ℃.Through field experiments,three fungicides including 50% dimethomorph water dispersible granules (WG),20% procymidone suspension concentrate (SC) and 72% cymoxanil · mancozeb wettable powder (WP),were selected to have better control effects on okra brown rot.The control efficiency of 50% dimethomorph WG diluted 600 times,1 200 times were significantly higher than the control fungicide (10% polyoxin WP) diluted 600 times by 15.2 percentage points and 14.2 percentage points,respectively,and were significantly higher than the control fungicide diluted 1 200 times by 13.8 percentage points and 12.8 percentage points,respectively.The control efficiency of 20% procymidone SC diluted 600 times and 1 200 times were significantly improved by 9.3 percentage points and 11.8 percentage points compared to the control fungicide diluted 600 times,respectively,and by 8.3 percentage points and 10.8 percentage points compared to the control fungicide diluted 1 200 times,respectively.The control efficiency of 72% cymoxanil · mancozeb WP was also significantly higher than that of the control fungicide.In summary,the suitable temperature for the occurrence of okra brown rot is 25-30 ℃.The main outbreak period in Heilongjiang area is from the end of June to the beginning of July.In production,50% dimethomorph WG,20% procymidone SC and 72% cymoxanil · mancozeb WP can be used to prevent and control the disease at the beginning stage,spraying once every 7 days and applying 3 times continuously,which can effectively control the occurrence of the disease.